D3928-00 – Standard Test Method Technical Guide

🎯 Scope and Significance of the Test Method

This test method, designated D3928 −00a (Reapproved 2018), covers the determination of the uniformity of gloss or sheen of a paint applied by brush to a test panel simulating an interior wall section. Variations in gloss or sheen caused by short wet edge time, poor leveling, and pigment orientation or flotation during application are evaluated visually.

Because both the application and the panel evaluation are very subjective, this test method should be used only for comparative testing within one laboratory. As noted in Section 8.1, ratings assigned by different laboratories do not usually agree. The values given in SI units are regarded as the standard.

The significance of this method lies in its practical application. When coatings are applied to large flat surfaces, film thickness varies, holidays occur, and lap marks appear. This test assesses a product’s ability to be touched up or applied without creating visually distracting areas of differing gloss or sheen, which is a critical attribute for both buyers and sellers.

📏 Specified Apparatus and Panel Configuration

To ensure consistency, the standard mandates specific brush geometries and a standardized test panel. All brushes must be polyester filament with a chisel tip. Previously used (broken-in) brushes are preferred to simulate realistic application conditions.